Obese individuals are at greater risk of various comorbidities including cancer, diabetes, and cardiovascular disease (CVD). Endocrine imbalances and dyslipidemia are likely contributors to the etiology of these diseases in obese individuals. / The objectives of this research project were: (1) to determine the effectiveness of a self-selected diet and exercise weight loss (WtL) protocol in overweight and obese women; (2) to investigate the effects of moderate WtL on hormones associated with the regulation of energy balance, blood lipid levels, and low density lipoprotein (LDL) particle size; (3) to characterize changes in cholesterol metabolism as a result of moderate WtL through an examination of factors that likely play a role in its modulation, specifically body composition and single nucleotide polymorphisms (SNP) in ATP binding cassette (ABC)G5 and ABCG8 transporter. / In carrying out these objectives, 35 women were included in a 24-week WtL trial. Hormone, lipids, and cholesterol metabolism were assessed at the end of two stabilization periods. During these periods, body composition was also measured via magnetic resonance imaging (MRI). WtL was achieved through a 20% decrease in energy intake using diet combined with a 10% increase in energy expenditure through physical activity. / Overall, participants lost an average of 11.7+/-2.5 kg. WtL resulted in improvements in blood lipid risk factors of CVD with minimal effect on LDL particle size. No associations were found between leptin, ghrelin, adiponectin, and insulin. Cholesterol synthesis decreased as a result of WtL, while cholesterol absorption and turnover did not change. Despite an absence of change in turnover, increases were predicted by decreases in visceral adipose tissue, and decreases in cholesterol absorption were associated with losses in total and upper body skeletal muscle. This study also showed that changes in cholesterol concentrations and metabolism after WtL are associated with SNPs in ABCG5 and ABCG8 genes. / These findings suggest that hormones important in the regulation of energy homeostasis may exert their effects independently. Moderate WtL results in cardioprotective changes in blood cholesterol levels primarily due to changes in cholesterol synthesis. These findings also indicate that the responsiveness of blood cholesterol levels and metabolism to weight loss is modulated by changes in body composition and SNPs in ABCG5 and ABCG8.

This study investigated the extraction of lipids and β-carotene from microalgae using microemulsions as an alternative to current solvents. Type I and type IV microemulsions composed of 4% lecithin, sorbitan monooleate, PEG-6-caprylic glycerides, and ethyl caprate were able extract lipids from lyophilized microalgae better than hexane and ethyl caprate. HPLC quantified the extracted β-carotene, with type IV microemulsions extracting the most β-carotene at 0.137±0.074% (w/w) of the total microalgae biomass after an hour. The growth recovery of the microalgae after extraction was observed over 2 weeks. Variability in the data prevented definite conclusions about the ability of algae to grow after extraction. The type IV extractions consistently showed some signs of survival. After two weeks, a pale-green colour was observed in the 15min and 1h extractions. This study showed that microemulsions can successfully extract lipids from microalgae; future work would apply microemulsion formulations to live algal cells for in-situ extraction.

This study investigated the extraction of lipids and β-carotene from microalgae using microemulsions as an alternative to current solvents. Type I and type IV microemulsions composed of 4% lecithin, sorbitan monooleate, PEG-6-caprylic glycerides, and ethyl caprate were able extract lipids from lyophilized microalgae better than hexane and ethyl caprate. HPLC quantified the extracted β-carotene, with type IV microemulsions extracting the most β-carotene at 0.137±0.074% (w/w) of the total microalgae biomass after an hour. The growth recovery of the microalgae after extraction was observed over 2 weeks. Variability in the data prevented definite conclusions about the ability of algae to grow after extraction. The type IV extractions consistently showed some signs of survival. After two weeks, a pale-green colour was observed in the 15min and 1h extractions. This study showed that microemulsions can successfully extract lipids from microalgae; future work would apply microemulsion formulations to live algal cells for in-situ extraction.

Thirty-three sedentary individuals (males, n=24; females, n=9) were studied to see the effects of 15-20 weeks of endurance training by walking and jogging on high-density lipoprotein, serum total cholesterol, and serum triglyceride. The training group (also called the moderately trained group) was then compared to a sedentary group and a highly trained group (25+ miles/week) to see what affect, if any, the endurance training had on their lipoprotein profile.Even though maximal oxygen uptake increased and percent fat decreased in the moderately trained group, no favorable differences mere seen in HDL-cholesterol, HDL-cholesterol/total cholesterol, serum total cholesterol, or serum triglyceride when comparing this group with the sedentary group.Significant changes did exist between the moderately trained and the highly trained groups when comparing HDL-cholesterol, HDL-cholesterol/total cholesterol, and serum triglyceride values.It appears that 15-20 weeks of endurance training does in fact increase one Is fitness level, but more training at a higher intensity and/or longer duration is needed to produce favorable changes in the lipoprotein profile.

The main goal in my project was find out if the rate of zinc crossing the bilayer was either due to the fluidity of vesicles or the level of oxidation of the vesicles.To measure the oxidation a simple procedure called the TBA Test was used to measure each PC tested. The fluidity measurement was a calculation using the temperature the vesicles went from gel to liquid crystalline phase and the experimental temperature.Measuring the rate at which zinc crossed the bilayer was done using spectral changes that occur as zinc binds with APIII, a metal chelator entrapped inside the vesicles. To measure these rates we used k', the rate constant at which zinc is crossing the bilayer at a certain concentration and k, the second order diffusion rate constant which is the slope of k' vs. [Zn].The rates at which zinc was crossing the bilayer for each PC was then compared to the fluidity and oxidation levels for each PC. There was no direct correlation between the rates and fluidity but there was a good linear correlation between the rates and oxidation.So it seemed as if oxidation was the main reason zinc was crossing the bilayer so we wanted to see if our measurements could be obtained by biological cells. The comparison showed that rates obtained by biological cells can only be matched by the vesicle models when there oxidation levels are found to be high.In conclusion we believe that the reason zinc is crossing the bilayer is due to oxidation that occurs to the vesicle and as oxidation increases so do the rates at which zinc crosses the bilayer. / Department of Chemistry

The fatty acid composition of whole tissue and plasma membrane fractions of mammary adenocarcinomas and normal mammary glands excised from Strong A female mice fed a 15% safflower oil and 15% tallow diets were studied. Previous work has indicated that high fat diets in general and high unsaturated fat diets in particular, influenced tumorigenesis. The mechanism is not clear. Alternig the normal composition and structure of the plasma membrane can result in altered physiological responses.The fatty acid composition of the dietary fat used in this study affected the fatty acid distribution of mammary gland tissue to a greater degree than tumor tissue. Tumor tissue had almost twice the percentage of linoleic acid as normal tissues (17.0% vs. 9.2%). Oleic acid was also elevated in tumor tissue (24.5% vs. 10.9). The normal tissues contained significantly higher proportions of eicosatrienoic acids (13.5%, 12.2%) than did tumorous tissues, regardless of diet (5.8%, 1.1%). It may be that some of these prostaglandin-active fatty acids in tumorous tissues have been diverted into prostaglandin synthesis.Results of this study indicate that the effect of dietary fat on plasma membranes of tumor cells and normal mammary gland cells was minimal. The saturated or unsaturated state of the fatty acids in the diet appear to play a role in the genesis of tumors by changing the availability of linoleic acid and other prostaglandinactive fatty acids.

The objectives of the present study were to examine the effects of dietary fat type and level of energy intake on hypothalamic leptin binding affinity and membrane fatty acid composition, circulating leptin levels, and body weight homeostasis in rats. Animals were fed diets containing tallow, safflower oil, or menhaden oil (20% wt/wt) for 10 wks, ad libitum or at 60% of ad libitum intakes. Specific leptin binding could not be detected in hypothalamic membrane homogenates; hypothalamic leptin levels were unaffected by diet or energy intake. Levels of tracer exceeding assay reference values were found in homogenates, suggesting intra-membrane binding. Excess tracer levels were weakly associated (p < 0.07) with the sum of hypothalamic phospholipid monounsaturates. Restriction lowered weight gain and food intakes (p < 0.0001 for both). In hypothalamic phospholipids, energy restriction lowered levels of 18:3(n-3) and increased levels of 20:1(n-9), 20:4(n-6), and 22:4(n-6) (p < 0.05, p < 0.02, p < 0.05, and p < 0.04, respectively). Fat type and energy level interactively affected hypothalamic levels of 20:4(n-6), 22:5(n-3) and 22:6(n-3) (p < 0.05, p < 0.006, and p < 0.05, respectively). Restriction lowered circulating leptin levels (p < 0.0001); overall plasma leptin levels were marginally associated (p < 0.07) with hypothalamic 16:0 concentrations. The results of the study support previous findings suggesting that leptin binding at the level of the hypothalamic membrane may not be detectable. The results also support the lack of a dietary fat effect on plasma leptin levels and levels of certain hypothalamic fatty acids, such as 20:4(n-6), 22:4(n-6), and 22:5(n-3), with energy restriction. The findings of the study suggest a link between increased membrane fluidity, increased binding affinity, and lower circulating leptin levels, promoting the possibility that the biological actions of leptin can be controlled through dietary effects on

No description available.

Thesis (M.S.)--Brigham Young University. Dept. of Physiology and Developmental Biology, 2006. / Includes bibliographical references (p. 50-58).

Thesis (Ph. D.)--University of Wyoming, 2005. / Title from PDF title page (viewed on Nov. 15, 2007). Includes bibliographical references (p. 175-198).